Dynamo electric machines

ABSTRACT

A method of connecting the conductors of the rotor of a dynamo electric machine to the segments of the commutator of the machine includes, starting with a pair of rotor winding conductors which are physically and electrically interconnected adjacent the end of a first conductor of the pair of conductors, with the end of said first conductor projecting beyond the end of the second conductor, engaging the projecting end of the first conductor with the surface of a portion of a segment of a commutator. The commutator is formed with a shoulder which defines one end of the surface thereof, and the projecting portion of the rotor conductor is engaged with said portion of the segment at least up to said shoulder. The conductor is then resistance welded to the segment, so that the first and second conductors are electrically connected to the segment.

United States Patent Allen 51 May 16, 1972 [73] Assignee: Joseph Lucas (Industries) Limited, Birmingham, England [22] Filed: Dec.31, 1970 [21] Appl.No.: 103,124

2,660,682 11/1953 Clokey et al ..29/597 X Chabot ..310/234 X Clark et al. ..310/234 X Primary Examiner-J. V. Truhe Assistant ExaminerL. A. Schutzman AttorneyHolman & Stern ABSTRACT A method of connecting the conductors of the rotor of a dynamo electric machine to the segments of the commutator of the machine includes, starting with a pair of rotor winding conductors which are physically and electrically interconnected adjacent the end of a first conductor of the pair of conductors, with the end of said first conductor projecting beyond the end of the second conductor, engaging the projecting end of the first conductor with the surface of a portion of a segment of a commutator. The commutator is formed with a shoulder which defines one end of the surface thereof, and the projecting portion of the rotor conductor is engaged with said portion of the segment at least up to said shoulder. The conductor is then resistance welded to the segment, so that the first and second conductors are electrically connected to the segment.

6 Claims, 3 Drawing Figures Patented May 16, 1912 I 3,663,791

INVENTOR Baum RM 411,

ATTORNEYS This invention relates to dynamo electric machines of the kind including a wound rotor and a commutator rotatable with the rotor, the conductors of the rotor being connected in pairs to the segmentsof the commutator.

' The object of the invention is to provide a convenient method of connecting the conductors of the rotor to the segments of the commutator.

A method according to the invention includes, starting with a pair of rotor winding conductors which are physically and electrically interconnected adjacent the end of a first conductor of the pair of conductors, with the end of said first conductor projecting beyond the end of the second conductor, the steps of engaging the projecting end of the first conductor with the surface of a portion of a segment of a commutator so that the end of the first conductor extends in contact with said portion of the segment 'at least up to a shoulder which defines one end of said-portion, and resistance welding the end of the first conductor to said portion of the segment, so that the first and second conductors are electrically connected to said segment.

One example of the invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a diagrammatic representation of a commutator and a pair of rotor winding conductors to be connected to a segment of the commutator;

F IG. 2 is a sectional view of the arrangement shown in FIG. 1, showing the conductor engaged with a commutator segment, and

FIG. 3 is 'a fragmentary perspective view of modified form of segment. 1

Referring to the drawings, the face type commutator 11 includes a central boss 12 by which the commutator is mounted on the rotor shaft of a dynamo electric machine. The commutator 11 includes a plurality of segments 13 which are supported on the boss l2,and insulated from one another, by an insulating body. The dynamo electric machine with which the commutator is associated includes a rotor carrying rotor windings, the windings of the rotor assembly being formed from copper strip. The conductors of the windings of the rotor can be considered in pairs, and each pair is to be connected to a respective segment of the commutator.

A pair of conductors 14,15 are led from the rotor assembly towards the commutator, the end portion of the conductor 14 being provided with a surface layer of tin-or tin-leadalloy approximately'0.0005 inches thick. The conductors 14,15 are resistance welded to one another at 16, adjacent the commutator, the tinned region of the conductor-l4 extending from the end of the conductor 14 beyond the weld 16. The free end of the conductor 15, at the side of the weld 16 remote from the rotor assembly, is severed so that the conductor 14 is longer than the conductor 15. The free end portion of the conductor 14 is then engaged with the peripheral surface of one of the segments 13, of the commutator. The length of the free end of the conductor 14 is such that the conductor 14 extends in contact with the surface of the peripheral portion of the segment across the full width of the peripheral portion of the segment, that is to say that the free end of the conductor 14 extends at least up to the shoulder defined at one end of the peripheral portion of the segment by the front, brush engaging surface of the segment. The respective length of the conductor 14 and the conductor 15 when the conductor 15 has been cut back are such that the free end face of the conductor 15 lies adjacent the rear face of the segment.

The commutator is then rigidly supported, and a first resistance welding electrode is engaged with the segment 13. A second resistance welding electrode is engaged with the outermost surface of the end portion of the conductor 14, and welding current is passed between the first and second electrodes through the end portion of the conductor 14 and the segment, while the second welding electrode applies pressure to the free end of the conductor 14, against the surface of the peripheral portion of the segment. The welding current, and the pressure applied b the second electrode is so controlled that-the end portion 0 the conductor 14 becomes resistance welded to the peripheral portion of the segment 13. In this way the segment is electrically connected to the conductor 14, and through the free end of the conductor 14 to the conductor 15. Moreover, the welding operation physically connects the end ofthe conductor 14 to the commutator segment, so that both conductors are held in place relative to the segment.

The modified form of segment 13 shown in FIG. 3 instead of having a part cylindrical peripheralsurface, is formed with an upstanding rib 17 which defines a riser. The outermost surface of the rib 17 is engaged by the conductor 14 in use, and is welded to the conductor 14 during the welding operation.

It will be appreciated that although the examples described above deal specifically with face commutators, the. method described can equally well be applied to barrel type commutators. Where the commutator is of the barrel type, then the shoulder which defines an end of the portion, of each segment, to which respective conductors 14 are welded, is constituted by one wall of a peripheral groove, or by a radially extending peripheral step on the commutator. The portions of the segments of the commutator to which the conductors 14 are welded can be provided with risers similar to the riser 17 shown in FIG. 3.

The provision of the shoulder which defines an end of the segment portion to which'the conductors 14 are welded, ensures a greater uniformity of weld between the segments and their respective conductors than is found in conventional arrangements, since by ensuring that the conductor extends over the surface of the portion at least up to the shoulder then the surface area of contact between each segment and its respective conductor will be substantially the same.

When all the segments have had their respective conductors welded in position the portions of the conductors 14 which project beyond the shoulderare removed by machining.

Having thus described my invention what I claim as new and desire to secure by Letter Patent is:-

1'. A method of connecting the conductors of the rotorof a dynamo electric machine to the segments of the commutator thereof including starting with a pair of rotor winding conductors which are physically and electrically interconnected adjacent the end of a first conductor of the pair of conductors, with the end of said first conductor projecting beyond the end of the second conductor, the steps of engaging the projecting end of the first conductor with the surface of a portion of a segment of a commutator so that the end of the first conductor extends in contact with said portion of the segmentat least up to a shoulder which defines one end of said portion and re sistance welding the end of the first conductor to said portion of the segment, so that the first and second conductors are electrically connected to said segment.

2. A method as claimed in claim 1 wherein said portion of .each segment of the commutator is constituted by an upstandeach segment is defined by one wall of a peripheral groove in the commutator.

6. A method as claimed in claim 4 wherein said shoulder of each segment is defined by a radially extending peripheral step on the commutator.

I x a n: s 

1. A method of connecting the conductors of the rotor of a dynamo electric machine to the segments of the commutator thereof including starting with a pair of rotor winding conductors which are physically and electrically interconnected adjacent the end of a first conductor of the pair of conductors, with the end of said first conductor projecting beyond the end Of the second conductor, the steps of engaging the projecting end of the first conductor with the surface of a portion of a segment of a commutator so that the end of the first conductor extends in contact with said portion of the segment at least up to a shoulder which defines one end of said portion and resistance welding the end of the first conductor to said portion of the segment, so that the first and second conductors are electrically connected to said segment.
 2. A method as claimed in claim 1 wherein said portion of each segment of the commutator is constituted by an upstanding riser integral with the remainder of the segment.
 3. A method as claimed in claim 1 or claim 2 wherein said commutator is of the face type.
 4. A method as claimed in claim 1 or claim 2 wherein said commutator is of the barrel type.
 5. A method as claimed in claim 4 wherein said shoulder of each segment is defined by one wall of a peripheral groove in the commutator.
 6. A method as claimed in claim 4 wherein said shoulder of each segment is defined by a radially extending peripheral step on the commutator. 